# encoding: utf-8

module OneApm
  # The EnvironmentReport is responsible for analyzing the application's
  # environment and generating the data for the Environment Report in OneApm's interface.
  #
  # It contains useful system information like Ruby version, OS, loaded gems,
  # etc.
  #
  # Additional logic can be registered by using the EnvironmentReport.report_on
  # hook.
  class EnvironmentReport

    # This is the main interface for registering logic that should be included
    # in the Environment Report. For example:
    #
    # EnvironmentReport.report_on "Day of week" do
    #   Time.now.strftime("%A")
    # end
    #
    # The passed blocks will be run in EnvironmentReport instances on #initialize.
    #
    # Errors raised in passed blocks will be handled and logged at debug, so it
    # is safe to report on things that may not work in certain environments.
    #
    # The blocks should only return strings or arrays full of strings.  Falsey
    # values will be ignored.
    def self.report_on(key, &block)
      registered_reporters[key] = block
    end

    def self.registered_reporters
      @registered_reporters ||= Hash.new
    end

    # allow the logic to be swapped out in tests
    def self.registered_reporters=(logic)
      @registered_reporters = logic
    end

    # register reporting logic
    ####################################
    report_on('Gems') do
      begin
        Bundler.rubygems.all_specs.map { |_gem| "#{_gem.name}(#{_gem.version})" }
      rescue
        # There are certain rubygem, bundler, rails combinations (e.g. gem
        # 1.6.2, rails 2.3, bundler 1.2.3) where the code above throws an error
        # in bundler because of rails monkey patching gem.  The below does work
        # though so try it if the above fails.
        Bundler.load.specs.map do |spec|
          version = (spec.respond_to?(:version) && spec.version)
          spec.name + (version ? "(#{version})" : "")
        end
      end
    end
    report_on('Plugin List'       ) { ::Rails.configuration.plugins.to_a }
    report_on('Ruby version'      ) { RUBY_VERSION                       }
    report_on('Ruby description'  ) { RUBY_DESCRIPTION                   }
    report_on('Ruby platform'     ) { RUBY_PLATFORM                      }
    report_on('Ruby patchlevel'   ) { RUBY_PATCHLEVEL.to_s               }
    report_on('JRuby version'     ) { JRUBY_VERSION                      }
    report_on('Java VM version'   ) { ENV_JAVA['java.vm.version']        }
    report_on('Logical Processors') { ::OneApm::Agent::SystemInfo.num_logical_processors }
    report_on('Physical Cores'    ) { ::OneApm::Agent::SystemInfo.num_physical_cores     }
    report_on('Arch'              ) { ::OneApm::Agent::SystemInfo.processor_arch         }
    report_on('OS version'        ) { ::OneApm::Agent::SystemInfo.os_version             }
    report_on('OS'                ) { ::OneApm::Agent::SystemInfo.ruby_os_identifier     }
    report_on('Database adapter'  ) do
      ActiveRecord::Base.configurations[OneApm::Probe.instance.env]['adapter']
    end
    report_on('Framework'       ) { Agent.config[:framework].to_s  }
    report_on('Dispatcher'      ) { Agent.config[:dispatcher].to_s }
    report_on('Environment'     ) { OneApm::Probe.instance.env }
    report_on('Rails version'   ) { ::Rails::VERSION::STRING       }
    report_on('Rails threadsafe') do
      ::Rails.configuration.action_controller.allow_concurrency
    end
    report_on('Rails Env') do
      if defined? ::Rails and ::Rails.respond_to?(:env)
        ::Rails.env.to_s
      else
        ENV['RAILS_ENV']
      end
    end
    # end reporting logic
    ####################################


    attr_reader :data
    # Generate the report based on the class level logic.
    def initialize
      @data = self.class.registered_reporters.inject(Hash.new) do |data, (key, logic)|
        begin
          value = logic.call
          if value
            data[key] = value

            Agent.record_metric("Supportability/EnvironmentReport/success", 0.0)
            Agent.record_metric("Supportability/EnvironmentReport/success/#{key}", 0.0)
          else
            Agent.logger.debug("EnvironmentReport ignoring value for #{key.inspect} which came back falsey: #{value.inspect}")
            Agent.record_metric("Supportability/EnvironmentReport/empty", 0.0)
            Agent.record_metric("Supportability/EnvironmentReport/empty/#{key}", 0.0)
          end
        rescue => e
          Agent.logger.debug("EnvironmentReport failed to retrieve value for #{key.inspect}: #{e}")
          Agent.record_metric("Supportability/EnvironmentReport/error", 0.0)
          Agent.record_metric("Supportability/EnvironmentReport/error/#{key}", 0.0)
        end
        data
      end
    end

    def [](key)
      @data[key]
    end

    def []=(key, value)
      @data[key] = value
    end

    def to_a
      @data.to_a
    end
  end
end